Chair, in particular office chair

Abstract

A chair, in particular an office chair, has a so-called synchronous mechanism in the form of a front seat support member stationary in relation to a chair column and a rear seat support member pivotable about a pivot axle in relation to the front seat support member and bearing a back-rest. A seat supports itself on the two seat support members. A blocking lever of a blocking mechanism and having a stop face is articulated on the rear seat support member at a distance from the pivot axle. This stop face is moved by gravity into engagement with a blocking face stationary in relation to the front seat support member. For releasing this locking, the blocking lever is lifted by a blocking actuator arm.

What is claimed is: 
     
       1. A chair, in particular an office chair, comprising a pedestal (2)   a chair column (4) projecting upwards from the pedestal (2)   a seat support (5) supported on the chair column (4) and having a front seat support member (6) joined to the chair column (4) and a rear seat support member (7) joined to the front, seat support member (6) by way of a pivot axle (8)   a seat (10) pivotably supported on the seat support members (6, 7)   a back-rest (15) secured to the rear seat support member (7)   an energy storing device (48), of which one end is positioned on the front seat support member (6) by means of a pivot hinge (59) and of which the other end is pivotably supported on the rear seat support member (7) at a distance (a) from the pivot axle (8), and   a blocking mechanism (61) for arresting the rear seat support member (7) in relation to the front seat support member (6), wherein the blocking mechanism (61) has a blocking lever (62) articulated on the rear seat support member (7) at a distance from the pivot axle (8) by means of a pivot joint (63) and provided with a stop face (64) which is pivotable into bearing engagement with a blocking face (65) stationary relative to the front seat support member (6) and releasable from this bearing engagement by means of a blocking actuator arm (67).     
     
     
       2. A chair according to claim 1, wherein the stop face (64) is turned away from the pivot joint (63) and the blocking face (65) faces the latter. 
     
     
       3. A chair according to claim 1, wherein the blocking lever (62) is pivotable upwards out of the bearing engagement of the stop face (64) with the blocking face (65). 
     
     
       4. A chair according to claim 1, wherein the blocking actuator arm (67) engages from below an end of the blocking lever (62) turned away from the pivot joint (63) to release the bearing engagement of the stop face (64) with the blocking face (65). 
     
     
       5. A chair according to claim 1, wherein the blocking actuator arm (67) is arranged on an actuating shaft (28) which is pivotably arranged in a suspension tube (9) supporting the seat (10) in the vicinity of a front edge (11) of the seat (10). 
     
     
       6. A chair according to claim 1, wherein the blocking actuator arm (67) is T-shaped with a transverse web (67a) engaging the blocking lever (62) from below. 
     
     
       7. A chair according to claim 6, wherein the blocking lever (62) has a forked end (66) which faces the blocking actuator arm (67) and with which the blocking actuator arm (67) engages. 
     
     
       8. A chair, in particular an office chair, comprising: a pedestal (2);   a chair column (4) projecting upwards from the pedestal (2);   a front seat support (5,6) fixed to the chair column (4);   a rear seat support member (7) joined to the front seat support member (6) by a pivot axle (8);   a seat (10) pivoted on the front seat support member and supported on the rear seat support member (7);   a back-rest (15) secured to the rear seat support member (7);   an energy storing device (48), having a first end positioned on the front seat support member (6) by means of a pivot hinge (59) and having another end distal the first end pivotably supported on the rear seat support member (7) at a distance (a) from the pivot axle (8); and   a blocking mechanism (61) for arresting the rear seat support member (7) in relation to the front seat support member (6);   wherein the blocking mechanism (61) has a blocking lever (62) articulated on the rear seat support member (7) at a pivot joint (63) spaced from the pivot axle (8), and provided with a stop face (65) stationary relative to the front seat support member (6), and releasable from bearing engagement with a blocking actuator arm (67).